• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.254-257
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• 2003

본 논문에서는 휴대폰에 사용되는 Multi-band 용 helical antenna 의 radiation pattern 을 체적화하기 위한 방법을 제안하고자 하였다. 일반적으로 GSM 휴대폰에 사용되는 안테나는 GSM, DCS 의 dual band 인 경우가 다수이며 추세에 따라 요즘은 PCS 등을 포함한 triple band 의 안테나가 많이 선호되고 있다. 이러한 multi band antenna 의 radiation pattern 에 영향을 미치는 변수로 본 논문에서는 ground 의 length 와 width 그리고 폴더쪽에 사용되는 LCD 의 ground 와 폴더쪽 기구물에 사용된 EMI spray 등의 변화를 통해 pattern 의 변화를 알아보고 이러한 변수를 조절하여 radiation pattern을 최적화하는 방법에 관하여 논하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.3
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• pp.233-238
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• 2003

With the growth of high speed circuit, unwanted system noise is increased and multipoint ground is used to reduce this noise. PCB screw ground structure has radiation noise by ground loop between screws. In order to solve this problem, in this paper, we proposed improved PCB ground structure. Proposed structure improves noise absorption by using microwave absorber and conductive copper tape. We measured radiation PCB noise in the range of 1 ㎓ to 3 ㎓ to investigate proposed structure usefulness. From these results, under 2 ㎓ range proposed structure has noise reduction by 2.62 dBuV/m, which compared with screw ground.

• KIEAE Journal
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• v.14 no.3
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• pp.65-70
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• 2014

The thermal environment in a small city rapidly deteriorates due to the urbanization and overpopulation. It is important to understand and predict the thermal environment in a city area. The thermal environment is highly affected by the solar radiation and temperature distributions changing over time periodically. To predict the thermal environment precisely, the solar radiation calculation including radiation strength, incidence angle, and thermal radiation between building surface and ground should be considered. In this study, the computational domain includes various artificial structures such as building, ground, asphalt, brick and grass. To consider the solar radiation, the unsteady state numerical calculation is performed from sun rise to mid-day (2:00pm). The numerical methods consist of solar load and one dimensional heat conduction through the boundaries to reduce the computational load and improve the flexibility of the calculation.

• Food Science of Animal Resources
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• v.34 no.4
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• pp.464-471
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• 2014

Ground lean pork was irradiated by an electron beam or X-rays to compare the effects of two types of radiation generated by a linear accelerator on the quality of Bologna sausage as a model meat product. Raw ground lean pork was vacuum packaged at a thickness of 1.5 cm and irradiated at doses of 2, 4, 6, 8, or 10 kGy by an electron beam (2.5 MeV) or X-rays (5 MeV). Solubility of myofibrillar proteins, bacterial counts, and thiobarbituric acid reactive substance (TBARS) values were determined for raw meat samples. Bologna sausage was manufactured using the irradiated lean pork, and total bacterial counts, TBARS values, and quality properties (color differences, cooking yield, texture, and palatability) were determined. Irradiation increased the solubility of myofibrillar proteins in a dose-dependent manner (p<0.05). Bacterial contamination of the raw meat was reduced as the absorbed dose increased, and the reduction was the same for both radiation types. Differences were observed only between irradiated and non-irradiated samples (p<0.05). X-ray irradiation may serve as an alternative to gamma irradiation and electron beam irradiation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.2
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• pp.135-143
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• 2012

This paper introduces the method to utilize a terminal ground as a radiator only using reactive components without an antenna structure. Characteristics of the proposed antenna is compared with that of the meander IFA on the same ground plane($40{\times}20mm^2$) for the bluetooth band. From simulation and measurement data, it is found that the proposed antenna using only capacitors provides the highest radiation efficiency. This is because of that the higher inductance reduces radiation resistance of a ground and the capacitor has a lower loss resistance comparing to that of the IFA or the inductor. In spite of the high radiation efficiency, the area ($5{\times}2.5mm^2$) of the proposed antenna is less than half of the area ($12{\times}2.5mm^2$) of the IFA.

• Preventive Nutrition and Food Science
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• v.9 no.4
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• pp.312-316
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• 2004

Sterilized raw ground pork was inoculated with Pseudomonas aeruginosa (PA) and Lactobacillus casei (LC) to investigate the relationship between microbial growth and 2-thiobarbituric acid reactive substances (TBARS) values. The analyses including microbial growth, pH, and TBARS values were performed during 3 weeks of storage at room temperature $(20^{\circ}C)$. The radiation-sterilized control sample did not show any microbial growth, but the samples inoculated at different levels (diluted twice vs non-diluted) exhibited differences until 1 week. However, the difference disappeared at weeks 2 and 3. The pH of raw ground pork inoculated with PA increased, but that of LC decreased. The pH of non-inoculated samples increased slightly after storage. The TBARS values in non-inoculated and LC inoculated with pork increased, but TBARS remained unchanged in samples inoculated with PA after 1 week. Results indicated that the microbial growth level and strains can influence the TBARS value of raw ground pork. Thus, it is important to use samples exposed to the same microbial conditions to compare the oxidation of lipids in meat samples.

• ETRI Journal
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• v.41 no.4
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• pp.528-535
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• 2019

The coupling mechanism of a loop-type ground radiation antenna is investigated in this paper. We use the equivalent circuit model of the antenna and a full-wave simulation to explain the coupling mechanism of the antenna. We analyze the effects of various antenna parameters on the coupling between the antenna element and the ground plane to examine the conditions for enhancing the coupling. Based on simulations with the equivalent circuit model, full-wave simulations, and measurements, we propose optimal design considerations for the antenna. The findings of this study will aid the design and understanding of loop-type ground radiation antennas for mobile devices.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.8
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• pp.8-14
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• 2008

In this paper, the effects of ground size on the characteristics such as input resistance, fractional bandwidth, and radiation efficiency of epsilon negative (ENG) zeroth order resonance (ZOR) antennas were investigated theoratically. Two types of ENG ZOR antennas were studied: mushroom ENG ZOR antenna with via and via-free defected ground structure (DGS) ENG ZOR antenna. It was confirmed that the ground size had more effects on the characteristics of a Via-free ZOR antenna than those of mushroom ZOR antenna with via. The via-free antenna could radiate properly with the required size of ground plane since the size of ground plane should exceed some critical value for DGS to suitably operate. As a height of substrate of mushroom ZOR antenna with via increased, the fractional bandwidth and radiation efficiency were improved. On the other hand, as a height of via-free ZOR antenna increased, the fractional bandwidth and radiation efficiency were degraded. Finally, a via-free ZOR antenna had an advantage of compactness even though its fractional bandwidth is narrow and its radiation efficiency is poor, compared with thoses of mushroom ZOR antenna with via.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.401-404
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• 2000

We designed and fabricated partially shorted MSA with a slot for 850 MHz on Copper-clad Laminate substrate, where the width of the radiation patch is identical with that of the ground plane and one side of the radiation patch is partially shorted to the ground plane. The radiation patterns of ZX, XY and ZY planes were measured. As a result, a better co and cross polarization lot ZX plane was obtained, compared to the partially shorted MSA without a slot.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.4
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• pp.424-430
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• 2012

A ground radiation antenna is designed using a capacitor connected between two ground points by a strip line. This paper analyzes the variations of radiation performance when changing the capacitor position. The surface current distribution of the ground antenna was investigated as the capacitor position is changed, in order to demonstrate the effects on the impedance bandwidth and antenna efficiency. Our antenna is for the Wi-Fi application. It is verified that the capacitor at the end of the strip line provides a wide impedance bandwidth(7.2 % at the 2.45 GHz frequency) and good antenna efficiency(measured as 66 % averaged over the overall Wi-Fi frequency band).